Rafael Sabatini 
Torquemada and the Spanish Inquisition 

In an endeavour to trace the Inquisition to its source it is not necessary to go as far back into antiquity as went Paramo; nor yet is it possible to agree with him that God Himself was the first inquisitor, that the first 'Act of Faith’ was executed upon Adam and Eve, and that their expulsion from Eden is a proper precedent for the confiscation of the property of heretics.
Nevertheless, it is necessary to go very far back indeed; for it is in the very dawn of Christianity that the beginnings of this organization are to be discovered.
There is no more lamentable lesson to be culled from history than that contained in her inability to furnish a single instance of a religion accepted with unquestioning sincerity and fervour which did not, out of those very qualities, beget intolerance. It would seem that only when a faith has been diluted by certain general elements of doubt, that only when a certain degree of indifference has crept into the observance of a prevailing cult, does it become possible for the members of that cult to bear themselves complacently towards the members of another. Until this comes to pass, intolerance is the very breath of religion, and—when the power is present—this intolerance never fails to express itself in persecution…